Photographic products and processes

ABSTRACT

This invention relates to photographic processes and products for forming an image in dye from a colorless precursor of a preformed image dye which is substituted with a moiety containing a thiazolidinyl group, said thiazolidinyl group (a) being capable of undergoing cleavage imagewise in the presence of an imagewise distribution of silver ion and/or soluble silver complex and (b) possessing a substituent on the carbon atom in the 2-position that undergoes a β-elimination reaction upon said imagewise cleavage, which moiety maintains the precursor in its colorless form at least until said thiazolidinyl group undergoes said cleavage. In a further embodiment, an imagewise distribution of a photographically useful reagent, which reagent may be, for example, a photographically active reagent, is released as a carbamic acid by a β-elimination reaction following the cleavage of a thiazolidinyl group whereby said reagent is provided with a solubilizing group at least during the initial stages of processing.

This is a division of application Ser. No. 500,391, filed June 2, 1983,now U.S. Pat. No. 4,468,449.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to the formation of dye images from asubstantially colorless precursor of a preformed image dye. In anotheraspect, this invention relates to photographic products and processesfor providing an imagewise distribution of a reagent such as aphotographically active reagent or an image dye-providing moiety and tonovel compounds useful therein.

2. Description of the Prior Art

U.S. Pat. No. 3,719,489 describes and claims photographic processesemploying initially photographically inert compounds which are capableof undergoing cleavage in the presence of the imagewise distribution ofsilver ions made available during processing of a silver halide emulsionto liberate a reagent, such as, a photographically active reagent or adye in an imagewise distribution corresponding to that of said silverions. In one embodiment disclosed therein, color images are produced byusing as the photographically inert compounds, color providing compoundswhich are substantially non-diffusible in the photographic processingcomposition but capable of undergoing cleavage in the presence of theimagewise distribution of silver ions and/or soluble silver complex madeavailable in the undeveloped and partially developed areas of a silverhalide emulsion as a function of development to liberate a more mobileand diffusible color-providing moiety in an imagewise distributioncorresponding to the imagewise distribution of said ions and/or saidcomplex. The subsequent formation of a color image is the result of thedifferential in diffusibility between the parent compound and liberatedcolor-providing moiety whereby the imagewise distribution of the morediffusible color-providing moiety released in the undeveloped andpartially developed areas is free to transfer. Color-providing compoundsuseful in the above processes form the subject matter of U.S. Pat. No.4,098,783, a continuation-in-part, of said U.S. Pat. No. 3,719,489.

Compounds disclosed in the aforementioned patents as useful inliberating a reagent in the presence of said silver ions and/or silvercomplex are sulfur-nitrogen compounds containing the group ##STR1## or--S--X--N═ wherein X is ##STR2## These 1,3-sulfur-nitrogen compounds maybe linear or cyclic in structure, and in a particularly preferredembodiment are cyclic compounds, such as, thiazolidine compounds whichcomprise a colored dye radical having the chromophoric system of an azo,anthraquinone, phthalocyanine or other dye and a thiazolidin-2'-ylmoiety which may be bonded directly to said dye radical or indirectlythrough an appropriate linking group. For example, the linking group maybe --CH₂ CH₂ O-- as in compound (33) at line 10, column 22, of said U.S.Pat. No. 3,719,489, or it may be ##STR3## as in compound (34) in column35 of said U.S. Pat. No. 4,098,783.

Copending U.S. patent application Ser. No. 500,366, now U.S. Pat. No.4,468,448 of Howard G. Rogers filed concurrently herewith is concernedwith the formation of a color image in a different manner using adifferent class of 1,3-sulfur-nitrogen compounds. Rather than relying onthe differential in diffusibility between the colored parent compoundand the liberated dye to form the color image, the ability of1,3-sulfur-nitrogen compounds to undergo silver ion assisted cleavage isutilized to provide an imagewise distribution of a colored image dyefrom a substantially colorless precursor of a preformed image dye byemploying a moiety comprising a 1,3-sulfur-nitrogen group to maintainsaid precursor in its substantially colorless form until said1,3-sulfur-nitrogen group undergoes cleavage imagewise to correspond tothe imagewise distribution of silver ion and/or soluble silver complexformed as a function of development of an imagewise exposedphotosensitive element.

Copending U.S. patent application Ser. No. 500,415, now U.S. Pat. No.4,468,451 of James W. Foley also filed concurrently herewith isconcerned with yet another class of 1,3-sulfur-nitrogen compounds whichmay be employed to form a color image from a substantially colorlessprecursor of a preformed image dye. As disclosed therein, the imagewisecleavage of the 1,3-sulfur-nitrogen group is used to activate theintramolecular cleavage of an amide group for providing a correspondingimagewise distribution of a photographically useful reagent which may becolored, for example, an image dye, or colorless.

The present invention is concerned with another class of compounds whichmay be used in forming dye images from a substantially colorlessprecursor of a preformed image dye and with their use in photographicproducts and processes.

SUMMARY OF THE INVENTION

According to the present inventon, a new class of compounds is providedwherein the imagewise cleavage of a thiazolidinyl group is used toactivate a β-elimination reaction for providing a correspondingimagewise distribution of image dye from a colorless precursor of apreformed image dye. In a further embodiment, an imagewise distributionof a photographically useful reagent is released as a carbamic acid by aβ-elimination reaction activated by the cleavage of a thiazolidinylgroup whereby said reagent is provided with a solubilizing group atleast during the initial stages of processing. The photographicallyuseful reagent released as a carbamic acid may be colored, for example,an image dye, or colorless.

It is, therefore, one object of the present invention to providephotographic products and processes for forming a dye image from acolorless precursor of a preformed image dye which is substituted with amoiety containing a thiazolidinyl group, said thiazolidinyl group (a)being capable of undergoing cleavage imagewise in the presence of animagewise distribution of silver ion and/or soluble silver complex and(b) possessing a substituent on the carbon atom in the 2-position thatundergoes a β-elimination reaction upon said imagewise cleavage, whichmoiety maintains the precursor in its colorless form at least until saidthiazolidinyl group undergoes said cleavage to activate saidβ-elimination reaction.

It is another object of the present invention to provide photographicproducts and processes for releasing an imagewise distribution of aphotographically useful reagent as a carbamic acid.

It is still another object of the present invention to provide novelthiazolidine compounds useful in the aforesaid photographic products andprocesses.

Other objects of the invention will in part be obvious and will in partappear hereinafter.

The invention accordingly comprises the processes involving the severalsteps and the relation and order of one or more of such steps withrespect to each of the others, and the product and compositionspossessing the features, properties and the relation of elements whichare exemplified in the following detailed disclosure, and the scope ofthe application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention,reference should be had to the following detailed description.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In one aspect, the present invention is concerned with a photographiccolor process which provides a dye image, said process comprisingphotoexposing a photosensitive element containing a silver halideemulsion, said silver halide emulsion having associated therewith acolorless precursor of a preformed image dye; developing said exposedsilver halide emulsion to form an image in developed silver and animagewise distribution of silver ions and/or soluble silver complex inthe partially developed and undeveloped areas of said emulsion; andforming as a function of said development a color image in dye from saidcolorless precursor, said colorless precursor of a preformed image dyebeing substituted with a moiety containing a thiazolidinyl group, saidthiazolidinyl group (a) being capable of undergoing cleavage imagewisein the presence of said imagewise distribution of silver ions and/orsoluble silver complex and (b) possessing a substituent on the carbonatom in the 2-position that undergoes a β-elimination reaction followingby the cleavage of said thiazolidinyl group, said moiety maintainingsaid precursor in its colorless form at least until said thiazolidinylgroup undergoes said cleavage. Preferably, the silver halide emulsion isa negative working emulsion and the color image is a positive image indye.

The colorless image dye-providing compounds that may be employed in theabove process may be represented by the formula

    T--L--Y--Z                                                 (I)

wherein T is a thiazolidin-2'-yl group capable of undergoing cleavage inthe presence of silver ions and/or soluble silver complex; L is a moietycapable of undergoing a β-elimination reaction following the cleavage ofsaid thiazolidin-2'-yl group; Y is a leaving group released by saidβ-elimination reaction; and Z is a preformed image dye which taken withY is a colorless precursor of said preformed image dye, said T--L--being substituted on said precursor such that the precursor ismaintained in its colorless form at least until said thiazolidin-2'-ylgroup undergoes said cleavage.

β-elimination reactions are well known in the art and involve thebreaking of bonds, for example, a C--N, C--O, C--S, C--Se, N--N, N--O orother bond to release a leaving group, which in this instance wouldcomprise the image dye. Any moiety that undergoes β-elimination may beemployed as L in formula I above, provided that the elimination rate forthe moiety taken with the silver assisted cleavage rate provides theimage dye at a photographically useful rate in a given photographicsystem. The rate constants for various leaving groups in eliminationreactions of β-substituted sulphones, β-substituted phenyl ketones andβ-substituted esters have been reported by Charles J. M. Stirling et al,J. Chem. Soc. (B), 1970, pages 672 and 684; Charles J. M. Stirling etal, J. Chem. Soc. Chem. Commun., page 941 (1975); and Charles J. M.Stirling, Acc. Chem. Res. 12, pages 198-203 (1979). Examples of someleaving groups from a carbon system include --SMe; --SPh; --SePh; --OPh;--OMe; --P(O)(OEt)₂ ; --NHTs; --C(Me)₂ NO₂ ; --N(Me)Ts; --N(Me)Ac;--N(Ph)Ac; --N(Ph)Ts; --N(Ph)CO₂ CH₂ pH and --N(Me)CO₂ Ph wherein Me,Et, Ph, Ac and Ts represent methyl, ethyl, phenyl, acetyl and tosyl,respectively.

In a further embodiment of the present invention, the moiety thatundergoes the β-elimination reaction comprises a carbamate group andreleases an imagewise distribution of a photographically useful reagentas a carbamic acid. Compounds useful for this purpose may be representedby the formula ##STR4## wherein T is a thiazolidin-2'-yl group capableof undergoing cleavage in the presence of silver ions and/or solublesilver complex; L is a moiety capable of undergoing a β-eliminationreaction following said cleavage of said thiazolidin-2'-yl group torelease ##STR5## R is hydrogen or a monovalent hydrocarbon group, e.g.,alkyl, aryl, alkaryl or aralkyl; and PHOTO is the radical of aphotographically useful reagent selected from a photographically activereagent and a color-providing moiety selected from an image dye, animage dye intermediate and when taken with ##STR6## is a colorlessprecursor of a preformed image dye, provided that when ##STR7## is saidcolorless precursor, said T--L-- is substituted on said precursor suchthat the precursor is maintained in its colorless form at least untilsaid thiazolidin-2'-yl group undergoes said cleavage.

Examples of photographically active reagents that may be releasedimagewise from the inert parent compound include a developmentrestrainer or arrestor, a silver halide solvent, a silver halidedeveloping agent, an antifoggant, a gelatin hardener, an emulsionstabilizer, a toning agent, an anti-bronzing agent and so forth.

The image dye released including the dyes formed from the colorlessprecursor compounds may comprise any of the general classes of dyesknown in the art, for example, nitro, azo, xanthene and anthraquinonedyes; also leuco, indicator, temporarily "color shifted" and other dyesthat take on a color change during or subsequent to processing toprovide the ultimately desired color for the dye image via oxidation,changes in pH, alkaline hydrolysis of a blocking group, etc. It will beappreciated that such a color change is precluded without removal of themoiety T--L-- only in those compounds where ##STR8## is the colorlessprecursor of a preformed image dye. Where the color-providing moiety isa colored image dye as distinguished from said colorless precursor orwhere it is a dye intermediate, the moiety T--L-- is used to provide,for example, an anchor and the dye image is formed as a result of thedifferential in diffusibility between the parent compound and theliberated color-providing moiety. Like the image dye released, the dyeintermediate released may be any molecule as previously employed thatreacts with another molecule to form a complete dye. For example, it maybe a phenolic, naphtholic, methylene or other coupler and/or a moleculethat reacts with a coupler, e.g., a quinonediimine or a carbonylcompound to form a complete dye.

Preferred compounds of the present invention for providing an image dyefrom a colorless precursor of an image dye may be represented by theformula ##STR9## wherein R⁰ is selected from alkyl, aryl, aralkyl andalkaryl; R¹ is selected from hydrogen, carboxy, N,N-dialkylcarboxamido,alkyl, aryl, aralkyl and alkaryl; R², R³ and R⁴ each are selected fromhydrogen, alkyl, aryl, aralkyl and alkaryl; R⁵ is selected from hydrogenand a group that can be removed upon cleavage of said thiazolidinylgroup to leave an electron pair, e.g., a carboxy group; R⁶, R⁷ and R⁸each are selected from hydrogen, alkyl, aryl, aralkyl and alkaryl; and Yis a leaving group released by a β-elimination reaction followingcleavage of said thiazolidinyl group; and Z is a preformed image dyewhich taken with Y is a colorless precursor of a preformed image dye.

Preferred compounds for releasing a photographically useful reagent as acarbamic acid may be represented by the formula ##STR10## wherein R⁰,R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸ have the same meaning given above; R⁹ ishydrogen, alkyl, aryl, aralkyl or alkaryl; and PHOTO is the radical of aphotographically useful reagent selected from a photographically activereagent and a color-providing moiety selected from an image dye, animage dye-intermediate and when taken with ##STR11## is a colorlessprecursor of a preformed image dye.

Where ##STR12## comprises the colorless precursor of a preformed imagedye, it may be, for example, ##STR13## wherein R⁹ has the same meaninggiven above and n is 0 or 1.

Typical aryl groups include phenyl and biphenyl and said alkyl groupscomprising R, R⁰, R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸ and R⁹ usually contain1 to 20 carbon atoms, such as methyl, ethyl, propyl, isopropyl,isobutyl, hexyl, dodecyl, octadecyl and eicosanyl. Said aralkyl may be,for example, phenyl-substituted alkyl wherein said alkyl usuallycontains 1 to 20 carbon atoms, and said alkaryl may be, for example,alkyl-substituted phenyl wherein said alkyl usually contains 1 to 20carbon atoms. When R¹ is N,N-dialkylcarboxamido, each alkyl usuallycontains 1 to 20 carbon atoms.

It will be appreciated that the above-denoted R to R⁹ groups may befurther substituted with, for example, amino, carboxy, hydroxy, alkoxy,sulfonamido or other appropriate group.

The compounds of the present invention can be synthesized in aconventional manner, for example, by reacting a 2-substitutedthiazolidine compound with another molecule comprising the selectedphotographic reagent to give the desired product or by reacting anaminoethanethiol with an aldehyde-substituted molecule comprising thephotographic reagent to give the desired product.

The following examples are given to further illustrate the presentinvention and are not intended to limit the scope thereof.

EXAMPLE 1

Preparation of the compound having the formula ##STR14##

One gram of the following carbamoyl chloride-isocyanate mixture##STR15## was added to approximately 20 ml of dry chloroform. To thismixture was added one gram of the thiazolidine alcohol of the formula##STR16## This reaction mixture was stirred at room temperature for twohours. Additional chloroform solvent was added so that any startingmaterial present as the HCl salt would be soluble. TLC in ether wasrecorded. The reaction mixture was evaporated and triturated with ether.The insoluble solid was presumed to be the HCl salt of the titlecompound. TLC had shown a considerable amount of dark material whichremained at the origin, so the solid was chromatographed on silica withchloroform as eluent. The amine and the title compound came off with thefront as a mixture. TLC showed a minor amount of amine plus anothercolored impurity. NMR showed mostly title compound that came off as freebase. The free base was soluble in ether and positions in NMR comparedwith those of the starting alcohol (free base).

The thiazolidine alcohol having the formula set out below was preparedas follows: ##STR17##

A mixture of 2-n-butylaminoethanethiol (4.5 g; 0.034 mole) and the dimerof β-hydroxy-n-butyraldehyde (3.0 g; 0.017 mole) in approximately 100 mlof benzene were refluxed under nitrogen using a Dean-Stark trap toremove water. (Water began to come over immediately and stopped afterabout 20 minutes.) Refluxing of the mixture was continued for one hourand then the benzene was removed by evaporation. The residue wasdistilled (boiling point 100° C. at 0.125 mm) to give the title compoundas a colorless oil. These thiazolidine intermediates form the subjectmatter of copending U.S. patent application Ser. No. 474,144 of RobertR. Arbree, William J. Cumming and Frank A. Meneghini filed Mar. 9, 1983,now abandoned.

EXAMPLE 2

Preparation of the compound having the formula ##STR18##

The compound of Example 1 (200 mg; 0.54 mmole) in 0.5 ml of anhydrousN,N-dimethylformamide (over 4A sieves) was added to sodium hydride (13mg; 0.54 mmole) in N,N-dimethylformamide under nitrogen. After stirringat room temperature for 11/2 hours, evolution of hydrogen had ceased.Methyl iodide (77 mg; 0.54 mmole) dissolved in N,N-dimethylformamide wasadded dropwise. Heat evolved. Stirring of the reaction mixture wascontinued at room temperature. Sodium iodide precipitated. The solutionof the carbamate anion was red. As the reaction with methyliodideproceeded, the color changed to orange. The time for complete colorchange was about 11/2 hours. Thereafter, the mixture was poured intowater, extracted with ether, the ether extract washed several times withwater, dried and evaporated. The yield of title compound was nearlyquantitative.

EXAMPLE 3

Preparation of the compound having the formula ##STR19##

The thiazolidine alcohol of the formula, ##STR20## (1.85 g) wasdissolved in about 25 ml dry chloroform. Solid o-nitrophenyl isocyanatewas added, and the reaction mixture was stirred over the weekend. It wasthen evaporated, and the oil residue was dissolved in petroleum etherand extracted above five times with water. The petroleum ether layer wasdried and evaporated. (NMR showed the desired product.) Some solidformed in the oil. It was insoluble in petroleum ether and was removedby dissolving the product in petroleum ether and filtering. Evaporationof the petroleum ether gave an orange oil which crystallized onstanding. The crystals were slightly soluble in isopropanol. Thepartially crystalline oil was triturated with isopropanol, filtered andthe crystals washed with isopropanol and dried to give approximately 400mgs of the title compound as pale yellow crystals (melting range 53°-55°C.

EXAMPLE 4

Preparation of the compound having the formula ##STR21##

The compound of Example 4 was prepared from the compound of Example 3(1.1 g; 1.86 mmole) according to the procedure given in Example 2 usingequimolar amounts, i.e., 1.86 mmole of both sodium hydride and methyliodide in N,N-dimethylformamide. Evaporation of the ether extract of thereaction mixture gave an orange oil. TLC showed the title compound asthe major product (which changed to orange in several hours) plus a veryminor amount of two yellow impurities.

As noted previously, in one embodiment the present invention isconcerned with the formation of a color image from certain colorlessimage dye-providing compounds comprising a colorless precursor of apreformed image dye. In this embodiment, the colorless compound may bepresent initially in the photosensitive element in a layer or layersother than the layer containing the light-sensitive silver halideemulsion, or it may be in the light-sensitive layer itself. For example,it may be in a layer on one side of the emulsion or in two layers, oneon either side of the emulsion. If desired, it may be separated from theemulsion layer by one or more spacer layers. Where the colorlesscompound is present in the light-sensitive layer, the compound should beinert, that is photographically innocuous in that it does not adverselyaffect or impair image formation. If not photographically innocuous, thecompound may be modified in a manner which does not interfere with thedevelopment process in any way, but which deactivates the compound sothat it does not affect adversely the light-sensitive emulsion. Ratherthan being disposed in the photosensitive element, the colorlesscompound may be initially contained in a layer associated with animage-receiving layer in processes such as diffusion transfer processeswhere image-receiving elements are employed.

The formation of color images according to the subject invention isapplicable to the preparation of both monochromatic and multicolorimages. For example, the colorless image dye-providing compounds of thisinvention may be employed in photographic systems utilizing multilayerphotosensitive elements comprising at least two selectively sensitivesilver halide emulsion strata having said colorless image dye-providingcompounds associated therewith which are processed simultaneously andwithout separation to provide a multicolor image. In such a structure, abarrier interlayer of silver complex scavenger, i.e., silver precipitantmay be used, to confine diffusion of soluble silver complex to theappropriate stratum. Also, filter layers containing, e.g., bleachablefilter dyes of the type described in U.S. Pat. Nos. 4,304,833, 4,358,118and 4,304,834 may be used to control the spectral composition of lightfalling on the underlying light-sensitive layer. Another usefulstructure for obtaining multicolor images is the screen type negativedescribed in U.S. Pat. No. 2,968,554 or that described in U.S. Pat. No.3,019,124.

According to one method of forming color images, both the image dyes andtheir colorless parent compounds comprising the colorless precursor of apreformed image dye are substantially non-diffusible from their initialposition in association with the photosensitive strata. To achieve therequisite non-diffusibility, the colorless parent compound may beappropriately substituted with an immobilizing group, e.g., a long chainalkyl group and the image dye released may be a dye that issubstantially non-diffusible by nature or it may be renderednon-diffusible by appropriate substitution with an immobilizing group,by including a mordant in the same layer with said image dye or by othermeans that would prevent the dye from diffusing from the photosensitiveelement.

Though the developed silver present in the photosensitive element afterimage formation and any remaining silver halide may be removed in aconventional manner, for example, by a bleach-fix bath, it is preferredto bleach the developed silver and to complex residual silver halide insitu. In a particularly preferred embodiment, the silver halide emulsionemployed is one which upon development contains low covering powersilver in the developed areas whereby the need for bleaching isobviated. In these embodiments, it will be appreciated that the silverhalide developing agents, the silver halide solvents and other reagentsemployed should be substantially non-staining.

Rather than forming monochromatic and multicolor images non-diffusiblefrom the photosensitive element, it will be appreciated that the imagedyes provided by the colorless parent compounds may be diffusible toform the color image on a single common image-receiving layer. In thisembodiment, the subsequent formation of a color transfer imagepreferably employs a differential in diffusibility between the colorlessparent compound and the liberated dye. This differential indiffusibility may be achieved in a known manner by the appropriateselection of an immobilizing group(s), such as a long chain alkyl oralkoxy group and/or solubilizing group(s), such as, hydroxy, carboxy orsulfo groups.

In the latter embodiments, where the image dyes released are diffusible,the photosensitive layer and the image-receiving layer may be inseparate elements which are brought together during processing andthereafter retained together as the final print or separated followingimage formation, or the photosensitive and image-receiving layers may bein the same element. For example, the image-receiving layer may becoated on a support and the photosensitive layer coated on the surfaceof the image-receiving layer. The processing composition may be appliedto the combined negative-positive element using a spreader sheet tofacilitate spreading the liquid composition in a uniform layer adjacentthe surface of the photosensitive layer. The image-receiving layercarrying the color image may be separated from the overlyingphotosensitive layer(s), e.g., with the aid of a stripping layer, or thecolor image may be viewed as a reflection print by employing alight-reflecting layer between the photosensitive and image-receivinglayers.

Illustrative of still other film units are those where the negative andpositive components together comprise a unitary structure and arelaminated and/or otherwise physically retained together at least priorto image formation. Generally, such film units comprise a plurality oflayers including a negative component comprising at least onelight-sensitive layer, e.g., a silver halide layer and a positivecomponent comprising an image-receiving layer which components arelaminated together or otherwise secured together in physicaljuxtaposition as a single structure.

Included among such structures are those adapted for forming a transferimage viewable without separation, i.e., wherein the positive componentcontaining the transfer image need not be separated from the negativecomponent for viewing purposes. In addition to the aforementionedlayers, such film units include means for providing a reflecting layerbetween the image-receiving and negative components in order to maskeffectively the silver image or images formed as a function ofdevelopment of the silver halide layer or layers and also to provide abackground for viewing the transfer image in the receiving component,without separation, by reflected light. This reflecting layer maycomprise a preformed layer of a reflecting agent included in the filmunit or the reflecting agent may be provided subsequent tophotoexposure, e.g., by including the reflecting agent in the processingcomposition.

The aforementioned layers are preferably carried on a support andpreferably are employed with another support positioned on the opposedsurface of the layers carried by the first support so that the layersare sandwiched or confined between the support members, at least one ofwhich is transparent to permit viewing of the final image. Such filmunits usually are employed in conjunction with means, such as, arupturable container containing the requisite processing composition andadapted upon application of pressure of applying its contents to developthe exposed film unit. Film units of this type are now well known andare described, for example, in U.S. Pat. Nos. 3,415,644, 3,415,645,3,415,646, 3,594,164 and 3,594,165.

The processing composition employed comprises an aqueous solution andusually, an aqueous alkaline solution of a silver halide developingagent and a silver halide solvent. The named ingredients may be presentinitially in the aqueous medium or may be present initially in thephotographic film unit, for example, in the emulsion and/orimage-receiving and/or spacer layers as heretofore suggested in the art.When such ingredients are present initially in the film unit, theprocessing composition is formed by contacting the product with asuitable aqueous medium to form a solution of these ingredients.

The alkali employed may be any of the alkaline materials heretoforeemployed, such as sodium or potassium hydroxide and like the developingagent and the solvent may be initially in a layer or layers of the filmunit.

The silver halide solvent also may be any of the heretofore knownmaterials, such as sodium or potassium thiosulfate, sodium thiocyanateor uracil; also the thioether-substituted uracils, pseudo-uracils andother compounds disclosed and claimed in U.S. Pat. No. 4,126,459; the1,3-disulfonylalkanes and cycloalkanes of U.S. Pat. Nos. 3,769,014 and3,958,992, respectively; or the alkanes containing an intralinearsulfonyl group and, e.g., an intralinear N-tosylsulfimido orN-tosylsulfoximido group as disclosed and claimed in U.S. Pat. No.4,107,176. Also, a silver halide solvent precursor may be used such asthose disclosed in U.S. Pat. No. 3,698,898 and as disclosed and claimedin copending U.S. patent application Ser. No. 382,479 filed May 27,1982, now U.S. Pat. No. 4,382,119.

Examples of silver halide developing agents that may be employed arehydroquinone and substituted hydroquinones, such as tertiary butylhydroquinone, 2,5-dimethyl hydroquinone, methoxyhydroquinone,ethoxyhydroquinone, 4'-methylphenylhydroquinone; pyrogallol andcatechols, such as catechol, 4-phenyl catechol and tertiary butylcatechol; aminophenols, such as 2,4,6-diamino-orthocresol;1,4-diaminobenzenes, such as p-phenylenediamine, 1,2,4-triaminobenzeneand 4-amino-2-methyl-N,N-diethylaniline; ascorbic acid and itsderivatives, such as ascorbic acid, isoascorbic acid and5,6-isopropylidene ascorbic acid and other enediols, such as,tetramethyl reductic acid; hydroxylamines, such asN,N-di-(2-ethoxyethyl)hydroxylamine,N,N-di-(2-methoxyethyl)hydroxylamine andN,N-di-(2-methoxyethoxyethyl)hydroxylamine; and heterocyclic compounds,such as, 1-phenyl-3-pryazolidone and4-methyl-4-hydroxymethyl-1-phenyl-3-pyrazolidone.

Usually, though not necessarily, the processing composition includes aviscosity-increasing reagent such as a cellulosic polymer, e.g., sodiumcarboxymethyl cellulose, hydroxyethyl cellulose, carboxymethylhydroxyethyl cellulose, etc; an oxime polymer, e.g., polydiacetoneacrylamide oxime; or other high molecular weight polymers.

In addition to the aforementioned ingredients, the processingcomposition also may contain antifoggants, preservatives and othermaterials as conventionally used in the art.

The processing composition may be applied to the photosensitive element,for example, by coating, dipping, spraying or by the use of a rupturablecontainer or pod such as disclosed in U.S. Pat. No. 2,543,181, thecontainer being positioned in the film unit so as to be capable uponrupturing of spreading its contents in a substantially uniform layer.

The photosensitive element may be any of those conventionally employedand generally comprises a silver halide emulsion carried on a base, forexample, glass, paper or plastic film, such as cellulose triacetatefilm, polyethylene terephthalate film, polystyrene film and polyolefinfilms, e.g., polyethylene and polypropylene films. The silver halide maybe a silver chloride, iodide, bromide, iodobromide, chlorobromide, etc.The binder for the halide, though usually gelatin, may be a suitablepolymer such as polyvinyl alcohol, polyvinyl pyrrolidone and theircopolymers.

Depending upon the particular photographic system, a mordant for the dyeimage may be used in association with the photosensitive layers asdiscussed above, or a separate image-receiving element may be employed.The image-receiving layer, i.e., dyeable stratum may comprise any of thematerials known in the art, such as polyvinyl alcohol, gelatin, etc.,preferably containing a mordant for the transferred image dye(s). Thedyeable stratum can be in the same element as the photosensitive layeror it may be in a separate element as appropriate for a givenphotographic process.

In diffusion transfer processes employing an aqueous alkaline processingcomposition, it is well known to employ an acid-reacting reagent in alayer of the film unit to lower the environmental pH followingsubstantial dye transfer in order to increase the image stability. Forexample, the previously mentioned U.S. Pat. No. 3,415,644 disclosessystems wherein the desired pH reduction may be effected by providing anacid-reacting layer adjacent the dyeable stratum. These layers maycomprise polymers which contain acid groups, e.g., carboxylic acid andsulfonic acid groups, which are capable of forming salts with alkalimetals or with organic bases; or potentially acid-yielding groups suchas anhydrides or lactones. Preferably the acid polymer contains freecarboxyl groups. Alternatively, the acid-reacting reagent may be in alayer adjacent to the silver halide most distant from theimage-receiving layer. Another system for providing an acid-reactingreagent is disclosed in U.S. Pat. No. 3,576,625.

An inert interlayer or spacer layer may be disposed between thepolymeric acid layer and the dyeable stratum in order to control or"time" the pH reduction so that it is not premature and interferes withthe development process. Suitable spacer or "timing" layers for thispurpose are described with particularity in U.S. Pat. Nos. 3,362,819;3,419,389; 3,421,893; 3,455,686; and 3,575,701.

The acid-reacting layer and associated spacer layer are usuallycontained in the image-receiving element in systems wherein the dyeablestratum and photosensitive strata are contained on separate supports,e.g., between the support for the receiving element and the dyeablestratum. In integral film units, these layers may be associated with thedyeable stratum, e.g., on the side of the dyeable stratum opposed fromthe photosensitive element or, if desired, they may be associated withthe photosensitive strata, as is disclosed, for example, in U.S. Pat.Nos. 3,362,821 and 3,573,043. In film units such as those described inthe aforementioned U.S. Pat. Nos. 3,594,164 and 3,594,165, they also maybe contained on the spreader sheet employed to facilitate application ofthe processing composition.

In addition to the aforementioned layers, the film units may containadditional layers as commonly used in the art, such as a layer ofantihalation dye, and/or a layer of filter dye arranged betweendifferentially color-sensitive emulsion layers. Depending upon theparticular photographic system, it may be desirable to use antihalationand filter dyes which become decolorized during photographic processing.

It will be understood that in the other embodiments of the presentinvention where the parent compound releases, for example, aphotographically active reagent, the parent compound may be disposedeither in the photosensitive element or in a second element dependingupon the particular photographic system and the photographic reagent tobe released. The parent compound and the reagent released can have thesame or different mobility characteristics as may be required for agiven process. As discussed above, the respective mobilizingcharacteristics can be adjusted in a known manner by appropriatesubstitution with immobilizing and/or solubilizing groups. Dependingupon the particular parent compound, it may be advantageous to employ acombination of immobilizing and solubilizing groups to render thecompound non-diffusible yet more wettable in the processing composition.Where it is desired to release, for example, a diffusible dye from acolored substantially non-diffusible parent compound anchored with asingle immobilizing group, the anchor should be positioned on the parentcompound such that upon cleavage, it will be on a fragment differentfrom the fragment released as the diffusible color-providing moiety.Also, it may be preferable to position the immobilizing group on thatportion of the parent compound that ultimately forms a complex with thesilver ion upon cleavage.

The following examples show by way of illustration, and not by way oflimitation, the utility of the subject compounds.

EXAMPLE I

Two photosensitive elements were prepared by coating a gelatin subcoatedpolyethylene terephthalate film base with a gelatino silver iodobromideemulsion. One of said photosensitive elements was coated at a coverageof 20 mgs/ft² of silver, and the other of said elements was coated at acoverage of 40 mgs/ft² of silver.

A second element containing a compound of the present invention wasprepared employing a component similar to that described in U.S. Pat.No. 3,647,437 (column 66, lines 46 to 59) which comprised a transparentpolyethylene terephthalate film base carrying the following layers.

(1) a polymeric acid layer

(2) a polymeric spacer (timing) layer

(3) a polymeric image-receiving layer.

To form said second element, the above component was coated (over theimage-receiving layer) with

(a) 100 mgs/ft² of poly-4-vinylpyridine containing 100 mgs/ft² of thecolorless image dye-providing compound of Example 1 (or 100 mgs/ft² ofthe colorless image dye-providing compound of Example 2) and

(b) 30 mgs/ft² of gelatin containing succindialdehyde hardener.

The photosensitive elements were given an exposure through a stepwedgeto white light of 2 mcs and superposed with said second elements. Alayer of an aqueous alkaline processing composition approximately 0.0020inch thick was distributed between said elements by passing the filmunits between a pair of pressure-applying rolls in the dark. Theprocessing composition comprised the following ingredients.

    ______________________________________                                        Water                     100     cc                                          Potassium hydroxide       5       g                                           Sodium sulfite            2       g                                           6-methylthiomethyl-2,4-dihydroxy-pyrimidine                                                             1.5     g                                           Tetramethyl reductic acid 6       g                                           Hydroxyethyl cellulose    3       g                                           Titanium dioxide          50      g                                           ______________________________________                                    

After applying said processing composition the film units weremaintained intact to provide an integral negative-positive reflectionprint, and at recorded time intervals, the maximum and minimumreflection densities were measured for the positive yellow images. Thedensities measured at given times are set forth in Table I below.

                  TABLE I                                                         ______________________________________                                        Cpd of Ex. 1                                                                              Cpd of Ex. 1  Cpd of Ex. 2                                        (20 mgs/ft.sup.2 Ag)                                                                      (40 mgs/ft.sup.2 Ag)                                                                        (40 mgs/ft.sup.2 Ag)                                       Dmax/             Dmax/         Dmax/                                  Time   Dmin     Time     Dmin   Time   Dmin                                   ______________________________________                                        10  min    0.37/0.25                                                                              10  min  --     10  min  0.38/0.33                        20  min    0.40/0.27                                                                              20  min  0.44/0.24                                                                            --     --                                 30  min    0.40/0.27                                                                              --     --     --     --                                   40  min    0.41/0.27                                                                              75  min  0.49/0.27                                                                            40  min  0.50/0.32                        2.5 hrs    0.47/0.28                                                                              3.5 hrs  0.52/0.29                                                                            2.5 hrs  0.95/0.52                        18  hrs    0.60/0.54                                                                              18  hrs  0.64/0.56                                                                            --     --                                 ______________________________________                                    

EXAMPLE II

A photosensitive element was prepared by coating a gelatin subcoatedpolyethylene terephthalate film base with a gelatino silver iodobromideemulsion at a coverage of 40 mgs/ft² of silver.

A second element was prepared in the same manner described in Example Iabove except that the coating (a) contained 150 mgs/ft² of the compoundof Example 4 in 100 mgs/ft² of poly-4-vinylpyridine.

The unexposed photosensitive element was superposed with said secondelement and one-half of the resulting sandwich was processed with alayer (0.0020 inch thick) of an aqueous 5% sodium hydroxide solutioncontaining 3% of hydroxyethyl cellulose and the other half of thesandwich was processed with a layer (0.0020 inch thick) of an aqueous 5%sodium hydroxide solution containing 1.5% of6-methylthiomethyl-2,4-dihydroxypyrimidine silver halide solvent and 3%of hydroxyethyl cellulose. The optical transmission densities weremeasured at given time intervals for the two halves of the sandwich andshowed the formation of dye from the colorless precursor. The resultsobtained are set forth in Table II below.

                  TABLE II                                                        ______________________________________                                        Time       Optical Transmission Density                                       (min.)     Without Solvent                                                                            With Solvent                                          ______________________________________                                        10         0.27         0.27                                                  27         0.24         0.32                                                  39         0.25         0.55                                                  57         0.28         0.73                                                  ______________________________________                                    

EXAMPLE III

A photosensitive element was prepared by coating a transparentpolyethylene terephthalate film base with the following layers.

(1) a layer containing 50 mgs/ft² of poly-4-vinyl-pyridine and 150mgs/ft² of the compound of Example 3,

(2) a layer of gelatin coated at a coverage of 100 mgs/ft²,

(3) a gelatino silver iodobromide emulsion layer coated at a coverage of60 mgs/ft² of silver, and

(4) a layer of gelatin containing succindialdehyde.

To show the formation of dye in the presence of silver halide complex,the unexposed photosensitive element was superposed with a secondelement similar to that described in U.S. Pat. No. 3,647,437 (column 66,lines 46 to 59) which comprised a transparent polyethylene terephthalatefilm base carrying the following layers.

(1) a polymeric acid layer

(2) a polymeric spacer (timing) layer

(3) a polymeric image-receiving layer.

The superposed elements were processed in the same manner using the sametwo processing compositions as in Example II above to show the formationof dye from the colorless precursor in the presence of silver halidecomplex. The optical transmission densities that were measured at giventime intervals are set forth in Table III below.

                  TABLE III                                                       ______________________________________                                                 Optical Transmission Density                                         Time       Without Solvent                                                                            With Solvent                                          ______________________________________                                         1 min.    0.13         0.14                                                   3 min.    0.14         0.15                                                  10 min     0.18         0.20                                                   1 hr      0.17         0.26                                                   1 day     0.26         0.36                                                   7 day     0.45         0.60                                                  ______________________________________                                    

It will be appreciated that the photographic systems of the presentinvention for providing an imagewise distribution of a photographicreagent may be used to provide dyes, dye intermediates and photographicreagents other than those specifically mentioned. Also, it will beappreciated that the present systems may be used with film structuresother than those illustrated.

Since certain changes may be made in the herein-defined subject matterwithout departing from the scope of the invention herein involved, it isintended that all matter contained in the above description should beinterpreted as illustrative and not in a limiting sense.

What is claimed is:
 1. A compound of the formula ##STR22## wherein R⁰ isselected from alkyl, aryl, aralkyl and alkaryl; R¹ is selected fromhydrogen, carboxy, N,N-dialkylcarboxamido, alkyl, aryl, aralkyl andalkaryl; R², R³ and R⁴ each are selected from hydrogen, alkyl, aryl,aralkyl and alkaryl; R⁵ is selected from hydrogen and carboxy; R⁶, R⁷and R⁸ each are selected from hydrogen, alkyl, aryl, aralkyl andalkaryl; R⁹ is selected from hydrogen alkyl, aryl, aralkyl and alkaryl;and PHOTO is ##STR23## wherein n is 0 or 1.